Which of the Following Describes a Flaw in the Methodology

Which of the following describes a flaw in the methodology used in surveys found in magazines?

A) Too many readers may respond, which may result in calculation errors.
B) The targeted audience may be too broad and therefore may not be representative of their readers.
C) Most respondents are readers of the magazine and therefore would not represent the general population.
D) Researchers are apt to adjust the findings so they seem acceptable to the reader.